Conventionally, there is a well known lighting apparatus for controlling a plant disease which controls a wavelength component of ultraviolet rays and emits it (refer to Japanese Laid-Open Patent Publication No. 2005-328734, for example). In the above apparatus, the ultraviolet rays are controlled to include a wavelength component in UV-B range (the wavelength range 280 to 340 nm) and set a wavelength component in UV-C range (the wavelength range 100 to 280 nm) to almost zero. This inhibits a spore formation and a hyphal growth of filamentous fungi which cause gray mold, powdery mildew, downy mildew, anthracnose, or the like and thereby has an effect to control the above plant diseases.
However, the technique disclosed by the Publication No. 2005-328734 cannot reliably inhibit the spore formation and the hyphal growth of the filamentous fungi causing the above plant diseases. Moreover, the reliable induction of resistance against the plant diseases is often difficult.